The long-term objectives of the proposed research are to work out the neural circuitry by which the medial preoptic area (MPOA) of the rostral hypothalamus influences maternal behavior in the rat and to understand the functon of the MPOA with respect to maternal behavior. Our specific aims can be divided into three categories: To identify specific brainstem termination sites for MPOA efferents important for maternal behavior; to identify significant sources of afferent input to the MPOA important for maternal behavior; to identify the neurotransmitters used in the neural pathways important for maternal behavior. By accomplishiung these aims we take a major step toward circuitry analysis and by understanding the functions of the structures with which the MPOA interacts we gain information on the mechanism by which the MPOA influences maternal behavior. The methodology to be employed will include: examining the effects of destroying particular neural structures and pathways on the maternal behavior of rats; the use of horseradish peroxidase histochemistry to trace neural pathways that might be important for maternal behavior; examining the effects of drugs, which influence particular neurotransmitter systems, on maternal behavior; the use of immunocytochemical techniques to identify possible peptide neurotransmitters in the neural circuitry of maternal behavior. The MPOA is involved in the reproductive behavior of all vertebrates, including primates. We view our work on the rat, a typical mammal, particularly with respect to hypothalamic neural organization, as providing basic and generalizable information on the role of the MPOA in the control of the motivational aspects of maternal behavior.